sudo apt-get install ddclient

gksudo gedit /etc/ddclient.conf

# Configuration file for ddclient generated by debconf
#
# /etc/ddclient.conf

pid=/var/run/ddclient.pid
protocol=dyndns2
#Utiliser 'use=web' si l'ordinateur est derrière un routeur
use=if, if=eth0
server=members.dyndns.org
login=login
password='pass'
site1.dyndns.org,site2.dyndns.org

invoke-rc.d ddclient restart